Without limiting the scope of the invention, its background is described in connection with nanoparticles. The physical properties (e.g., high surface-to-volume ratio, elevated surface energy, increased ductility after pressure loading, higher hardness, larger specific heat and the like) of nanoparticles have let to increased applications in the material-directed industry and material science. For example, a variety of metal nanoparticles have been used to catalyze numerous reactions.
The size of nanoparticles range from the 0.5 to 100 nm and the electronic energy band configuration is a size-dependent property, which in turn affect the physical and chemical properties. A fundamental distinction between nanoparticles and their bulk materials is that the fraction of surface atoms and the radius of curvature of the surface are comparable with the lattice constant. As a result, the nanostructured catalysts have a higher catalytic activity of as compared with their analogues based on bulk materials. The methods of forming nanoparticles are known to the skilled artisan and include formation by combining atoms (or more complex radicals and molecules) and by dispersion of bulk materials, e.g., thermal evaporation, ion sputtering, reduction from solution, reduction in microemulsions and condensation.
For example, U.S. Pat. No. 6,537,498 entitled, “Colloidal particles used in sensing arrays” discloses chemical sensors for detecting analytes in fluids having a plurality of alternating nonconductive regions and conductive regions of conductive nanoparticle materials. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions.
Another example includes U.S. Pat. No. 6,972,173 entitled, “Methods to increase nucleotide signals by Raman scattering” teaches methods and apparatus relating to nucleic acid sequencing by enhanced Raman spectroscopy using nucleotides covalently linked to silver or gold nanoparticles. Electrocatalysis at nanoparticles, for analytical purposes, has been described in the art; however, such descriptions involve large numbers of nanoparticles, at least hundreds of thousands, as monolayer or near monolayer films on electrode surfaces.1 